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Commit dd6bd0d9 authored by Matthew Wilcox's avatar Matthew Wilcox Committed by Linus Torvalds
Browse files

swap: use bdev_read_page() / bdev_write_page() 



By calling the device driver to write the page directly, we avoid
allocating a BIO, which allows us to free memory without allocating
memory.

[akpm@linux-foundation.org: fix used-uninitialized bug]
Signed-off-by: default avatarMatthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 47a191fd

mm/page_io.c

+20 −1
Original line number Diff line number Diff line
@@ -248,11 +248,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) 
	return ret;

}



static sector_t swap_page_sector(struct page *page)

{

	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);

}



int __swap_writepage(struct page *page, struct writeback_control *wbc,

	void (*end_write_func)(struct bio *, int))

{

	struct bio *bio;

	int ret = 0, rw = WRITE;

	int ret, rw = WRITE;

	struct swap_info_struct *sis = page_swap_info(page);



	if (sis->flags & SWP_FILE) {
@@ -297,6 +302,13 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, 
		return ret;

	}



	ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc);

	if (!ret) {

		count_vm_event(PSWPOUT);

		return 0;

	}



	ret = 0;

	bio = get_swap_bio(GFP_NOIO, page, end_write_func);

	if (bio == NULL) {

		set_page_dirty(page);
@@ -338,6 +350,13 @@ int swap_readpage(struct page *page) 
		return ret;

	}



	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);

	if (!ret) {

		count_vm_event(PSWPIN);

		return 0;

	}



	ret = 0;

	bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read);

	if (bio == NULL) {

		unlock_page(page);